There are several good route planners out there, Tyre is not quite as good as some of the others although it has some good points. ITN Converter is also a good planning tool, MRA (MyRouteApp) is getting better and better and almost does it all. Although to get all of the good features you need a Gold membership.
Having played with MyRouteApp under Rae's guidance, I can vouch that's it's pretty comprehensive.
For about £3/month, amongst other features, you can compare TomTom and Garmin's opinion of a route. Occasionally it's an eye-opener, as I found out on the Welsh routes.
It's a vital feature if you intend to share a route with others.